B6(Cg)-Cd8a^{tm1.1(cre)Koni}/J

Stock number: 017562
Product name: CD8a-Cre knock-in , Cd8a^cre
Research areas: Immunology, Inflammation and Autoimmunity Research, Research Tools

Description

Cd8a^cre has Cre recombinase and IRES inserted into the start codon of the CD8 antigen, alpha chain locus (Cd8a) - resulting in Cre expression and de novo CD8a expression. Endogenous CD8a expression is diminished. These mice may be useful for deletion of genes of interest in CD8a expressing cells.

Detailed description

In this strain Cre-recombinase and an internal ribosome entry site (IRES) are expressed under control of the endogenous CD8 antigen, alpha chain (Cd8a) promoter, allowing for Cre-recombinase expression and de novo CD8a expression. CD8a is a cell surface glycoprotein found on dendritic cells, intestinal intra-epithelial cells, and CD8 T cells. The donating investigator reports that heterozygous mice have a 35% reduced expression of CD8a on CD8a-expressing cells, with no change in the number of CD8 T cells in lymphoid organs. Homozygous mice have 13% of the endogenous level of CD8a expression and have greatly reduced numbers of CD8 T cells. Homozygotes are viable, fertile, and normal in size. When crossed with a strain containing a loxP site-flanked sequence of interest, Cre-mediated recombination results in deletion of the flanked sequence in CD4^-CD8a⁺ and some CD4⁺CD8a^- expressing dendritic cells, showing potential origin of both lines from CD8a+ lineage. These mice may be useful for deletion of genes of interest in CD8a expressing cells.

Development

A targeting vector was designed to insert a Cre-recombinase coding sequence, a neomycin resistance (neo) cassette, and an internal ribosome entry site (IRES) into the start codon of the CD8 antigen alpha chain (Cd8a) gene. The construct was electroporated into C57BL/6NHsd-derived LK-1 embryonic stem (ES) cells. Correctly targeted ES cells were injected into blastocysts and the resulting chimeric males were bred to C57BL/6 females. Offspring were then bred to B6.Cg-Tg(ACTFLPe)9205Dym/J mice (Stock No. 005703) to delete the neo cassette. The resulting mice were backcrossed to C57BL/6J for at least 3 generations to generate a colony of Cd8a^cre mice. Upon arrival at The Jackson Laboratory, mice were bred to C57BL/6J (Stock No. 000664) for at least one generation.

Allele

Symbol: Cd8a^{tm1.1(cre)Koni}
Name: targeted mutation 1.1, Pandelakis A Koni
MGI accession ID: MGI:5294414
Generation method: Targeted
Attributes: Recombinase-expressing
Marker symbol: Cd8a
Marker name: CD8 antigen, alpha chain
Chromosome: 6
Strain of origin: C57BL/6NHsd
Expressed genes: cre,cre recombinase,bacteriophage P1
Site of expression: Cre-mediated recombination results in deletion of the flanked sequence in CD4-CD8a+ and some CD4+CD8a- expressing dendritic cells,
Molecular note: A targeting vector was designed to insert a cre-recombinase coding sequence, a neomycin resistance cassette, and an internal ribosome entry site (IRES) into the start codon of the CD8 antigen alpha chain (Cd8a) gene. The construct was electroporated into C57BL/6NHsd-derived LK1 embryonic stem (ES) cells. Chimeras were bred to C57BL/6 animals. Offspring were crossed to Flp-expressing mice to delete the neo cassette.